Over the last 3 years we have been involved in behavioral treatment of young autistic children (children less than 46 months of age if echolalic, and 40 months of age is mute). We have randomly assigned such children to 2 groups: Treatment I which receives more than 20 hours of treatment per week, and Treatment II, which receives less than 10 hours per week. As an added control some children in Treatment I are held in ("waiting list") baseline for varying periods of time (3, 6, and 9 months) before treatment is commenced. Pretreatment assessment includes a psychiatric/neurological evaluation, behavioral recordings of free-play and social behavior, psychological testing (the Bayley and Vineland), autism diagnostic checklist, etc. Treatment is modeled on a behavior modification framework, with emphasis on training the parents as the child's therapist. Post-treatment measures include the child's ability to function independently in and adequately adjust to, and learn from, normal school placement. To date we have treated 16 children in Treatment I, and have data on 9 children in Treatment II. Preliminary data suggests a recovery rate of 56% in Treatment I, and 0 to 11% in TreatmentII. The project does also report on basic research into autism in general, as it relates to the assessment of auditory and visual acuity, perceptual-attentional deficits, variables effecting echolia and self-destructive behavior and research on sensory-perceptual reinforcing stimuli.